The present invention relates to a drive arrangement for a machine for applying sealant to lids that includes a turret head driven by a drive motor to rotate about a vertical axis and equipped with a plurality of sleeve shafts that are provided with plates for holding lids, with the sleeve shafts being mounted for rotation about axes arranged parallel to the vertical axis of the turret head. Each sleeve shaft is provided with a pinion that is in engagement with a ring of teeth that rotates about the vertical axis and relative to the turret head.
A drive for a machine for applying a sealant material into lids is disclosed in U.S. Pat. No. 4,262,629. The lids are delivered to one station of a rotating turret or machine head provided with a plurality of lower sleeve shafts and respective upper resilient counterholders and spray guns with a liquid sealant or rubberizing substance. The sleeve shafts are provided with upper plates and are slidably and rotatably mounted within the machine head. During rotation of the machine head, the sleeve shafts are raised and the plates push the lids against the counterholders. Upon further rotation of the machine head, the sealant is supplied to the inner edge of the lid from the associated spray gun. Due to the rapid rotation of the sleeve shafts and lids, the sealant distributes itself uniformly. In the prior art machines for applying sealant to lids, the ring of teeth with which the pinions of the sleeve shafts are in engagement is driven by way of a number of drive transmission means by the same main motor as the turret head itself. Although the turret head and the revolving ring of teeth rotate at different rates, they are rigidly connected with respect to their drives, that is, their rotational rates are at a constant ratio. If now the turret head stops due to an operational malfunction, the rotating ring of teeth also stops and the sleeve shafts are unable to rotate any further. The sealant or rubberizing substance which is dispensed onto a lid when the turret head is braked or stops, is no longer able to flow properly and an unusable lid results.
Another drawback of the prior art drive arrangement is that if the rate of rotation of the sleeves relative to the turret head is to be changed, for example, if a different size lid is employed (i.e. the lid diameter changes), at least one pair of gears must be exchanged in order to change the transmission ratio.